Façade system

ABSTRACT

A plank (10) for a façade system comprises a facia (12), a joining lip (20), and a hook (30). The joining lip (20) is recessed behind and extends alongside the facia (12) to overlap with an adjacent plank. The hook 30 extends behind the facia to engage a wall-mounted retainer (38, FIG. 3D). The plank 10 comprises a rail 26 to conceal the hook (30). In one aspect, the rail 26 extends beyond the hook to abut the wall, to restrict a tilt of the plank. In one aspect, the joining lip 20 comprises alignment features (22) for positioning another retainer (40, FIG. 3D). In one aspect, the facia (12) comprises blind grooves (52, FIG. 8B) mimicking inter-plank interstitial grooves. The aspects individually and combined reduce the resources required for covering a large wall area with aligned cladding facias.

CROSS-REFERENCE TO RELATED APPLICATION DATA

This is a continuation of U.S. patent application Ser. No. 16/633,093,filed Jan. 22, 2020, which is a U.S. National Stage Application ofPCT/GB2018/052081, filed 24 Jul. 2018, titled Façade System, whichclaims the benefit of and priority to Great Britain Application No. GB1712020.5, filed 26 Jul. 2017, the disclosures of which are incorporatedhere in their entirety.

FIELD OF THE INVENTION

This invention relates to extruded plank systems, typically made ofextruded aluminium or plastics, for providing a weather-proof externalcovering to buildings such as an industrial building made principally ofmetal or concrete support beams which impart strength to the building,with the extruded plank system providing weather proofing, egrain-protection cladding, and/or an aesthetically pleasing outwardappearance.

BACKGROUND

Extruded plank systems for covering industrial buildings, or buildingsin general, comprise a succession of extruded panels fixed to a wallstructure such as an array of vertical beams, the planks being arrangedin a side-by-side relationship to each other, secured in place to thewall structure by fasteners, which may typically be in the form of aninsulating panel itself fixed to the wall structures via elongatefasteners driven therethrough.

Extruded planks are typically made of aluminium, with each successivepanel being hooked at its lower end to engage the hooked end of apreviously installed panel before being fixed in place, the paneltypically being supported by being held in its desired position by aco-worker while the plank is secured in place with fasteners.

The present invention seeks to provide advanced mounting structures thatmaintain a sufficient degree of rigidity.

Prior to fixation to a walling structure, some effort is directed toensuring that the planks are aligned as intended. For instance, railsmay have to overlap to provide an effective rain screen or flashing, orto provide a neat appearance. To achieve a desired degree of alignmentrelative to a fixed plank (eg the fixed plank may be a lower plank of asuccession of planks installed from the base to the top of a building),a co-worker may hold a spacer in place before positioning a successiveplank, such that the spacer sits temporarily on the fixed (lower) plankto support the successive (upper) plank that sits on the spacer until itis fixed to the building. Once the successive plank is fixed to thebuilding, the spacer can be removed and be used for the next plank. Thespacer ensures an even interstitial joint spacing between adjacentplanks. The alignment requirements increase with increasing façade areasand when smaller planks are used.

The present invention provides various aspects to facilitate existingcladding procedures.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there isprovided a plank for an extruded plank façade system as defined in claim1. The façade system comprises a plurality of such planks as claddingsuitable for a vertical walling structure. The plank is of the typecomprising a facia, a joining lip, and an attachment hook structure.

The joining lip is recessed behind the facia and extends along a side ofthe facia to be at least partially overlapped by an adjacent facia ofanother plank to be provided and to define at least part of a jointgroove between the facia and the adjacent facia.

The attachment hook structure extends back behind the facia to allow theplank to engage, via the attachment hook structure, a retainer fixed tothe walling structure.

The plank further comprises a rail to at least partially conceal theattachment hook structure.

In the first aspect, the rail extends back from the facia beyond theattachment hook structure, whereby, when the plank is attached to thewalling structure by way of the attachment hook structure on theretainer, the rail abuts the walling structure, thereby limiting a tiltof the plank about the attachment hook structure.

In accordance with a second aspect of the present invention, there isprovided a plank for an extruded plank façade system as defined in claim2. The façade system comprises a plurality of such planks as claddingsuitable for a vertical walling structure. The plank is of the typecomprising a facia, a joining lip, and an attachment hook structure.

The joining lip is recessed behind the facia and extends along a side ofthe facia to be at least partially overlapped by an adjacent facia ofanother plank to be provided and to define at least part of a jointgroove between the facia and the adjacent facia.

The attachment hook structure extends back behind the facia to allow theplank to engage, via the attachment hook structure, a retainer fixed tothe walling structure.

The plank further comprises a rail to at least partially conceal theattachment hook structure.

In the second aspect, the joining lip comprises a plurality of alignmentfeatures for positioning another retainer to be provided, the otherretainer to be engaged by an adjacent plank, wherein the alignmentfeatures are arranged on the joining lip at different distances from thefacia such that aligning the other retainer with one of the alignmentfeatures defines an interstitial distance of the joint groove betweenthe facia and the adjacent facia.

In some embodiments of the second aspect, the rail extends back from thefacia beyond the attachment hook structure, whereby, when the plank isattached to the walling structure by way of the attachment hookstructure on the retainer, the rail abuts the walling structure, therebylimiting a tilt of the plank about the attachment hook structure.

It is understood that the plank of the different aspects of theinvention has a longitudinal extension. The principal parts of the plankcan be described with reference to a cross-section perpendicular to thelongitudinal extension.

The plank is intended for horizontal or vertical mounting to a verticalbacking system, the backing system usually consisting of laterallyspaced apart rails or mullions, by way of a retainer arrangement. Theretainers of the retainer arrangement are mounted to the mullions withfasteners, such as bolts. In one arrangement described below, theretainer arrangement is provided by a bolt with integral retainer. Theplank is positioned, by way of the attachment hook structure, on oragainst one or more retainers of the retainer arrangement.

It is understood that the joining lip extends along one side of theplank, usually along a longer elongate side of the plank, so as to beoverlapped by an adjacent plank.

By walling structure, the underlying fix building structure is meant,and this may include previously installed planks. As will be seen below,a successive plank abutting the walling structure may abut its preceding(lower) plank fixed to the building.

The retainer may be fixed to the walling structure via (through) apreceding plank. The retainer may fix the preceding plank to the wallingstructure and serve as support for the succeeding plank. The retainermay be provided by a structure of the preceding plank. The retainer canbe positioned on the joining lip, such that the joining lip is fastenedto the walling structure with the fastener of the retainer.

The rail may be part of a flashing structure, provided to overlap withan adjacent plank so as to improve the rainproof properties of thefaçade system.

The facia is understood to constitute the exterior side of the plankwhen installed on a building. The back of the plank is thebuilding-facing side. When the plank is mounted to a walling structureof a building, a component on the back of the plank extends closer tothe walling structure the further it extends back from the plank.

The invention facilitates the installation of multiple planks in analigned fashion. The first aspect of the invention facilitates atemporary anchoring of a plank against the retainer, because once theattachment hook structure is held on or against the retainer, the railprovides a support leg function that inhibits a tilt of the plank aboutthe retainer. The rail can be designed within tight tolerances topractically avoid tilting altogether, although it is understood thatthis may also depend to some extent on the smoothness of the wallingstructure. The rail may abut the joining lip of a preceding plank, andin that case the rail may be designed taking into account the sheetthickness of the corresponding joining lip.

For assemblies in which a subsequent plank is to be installed aboveanother plank, the support leg has been found to temporarily prop up,and thereby stabilise, the subsequent plank sufficiently, even while thejoining lip abuts the walling structure and before the joining lip issecurely fixed to the walling structure. This allows the installation tobe carried out by one person, rather than requiring a second person tomaintain an alignment until the plank is securely fixed to the wallingstructure.

The second aspect of the invention facilitates the maintaining of one ofseveral pre-defined distances between two adjacent facias. This avoidsthe need for a separate, temporary spacer component to be temporarilypositioned between planks, because due to the alignment features on thelip of the plank, a permanent retainer to be provided can be relied onas providing the spacer function. Not requiring a temporary spacercomponent reduces the number of components to be carried or handled by aworker, and further reduces the requirement for a co-worker to assistwith the installation of the cladding.

Any embodiments of the first and second aspects may be combined tofacilitate the cladding installation procedure, because they allow theretainer to be used as alignment feature without the need for anadditional alignment tool, such as a spacer. Thus, the installation timecan be reduced as co-workers that would otherwise be required to assistwith the installation of a cladding system can be redeployed to progressthe cladding installation on a different wall section.

In some embodiments, the attachment hook structure has a contact levelwith the walling structure where it attaches to the retainer, whereinthe rail has a contact level with the walling structure where itcontacts the walling structure, and wherein the contact levels of theattachment hook structure and of the rail are spaced apart less than thewidth of the joining lip.

In other words, for two planks of the same design the joining lip of thefirst plank is at least as wide as the space between the engagement lineof the attachment hook structure and the contact area of the rail withthe walling structure. This ensures an overlap between two adjacentplanks in a manner that, when a first and a second plank are installedadjacent to each other, the joining lip of a first plank extends atleast to the attachment hook structure of the second plank.

In some embodiments, the joining lip comprises a plurality of lipprotrusions or lip recesses, the lip protrusions or lip recessesconstituting alignment features for said retainer.

In some embodiments, the lip protrusions are provided by ridges, and/orwherein, respectively, the lip recesses are provided by grooves.

The ridges and/or grooves may extend parallel to the edge of the facia.A feature extending in parallel is suitable for extruded planks.

In some embodiments, the plurality of lip protrusions or lip recesses,respectively, are unequally spaced apart with respect to the distancefrom the facia.

Unequally spaced apart alignment features help to ensure the correctalignment of the retainer with the joining lip. As set out below, theretainer-to-be-provided may comprise alignment features that arecorrespondingly unequally spaced apart in a manner that allow theretainer to positioned on the joining lip in one of only a fewconfiguration options.

In some embodiments, the attachment hook structure comprises aretainer-engaging face that is inclined relative to the plank plane,such that, the deeper the attachment hook structure is set into theretainer, the closer the plank is held on the walling structure.

This facilitates the engagement of a plank with the retainer on thewalling structure by allowing the plank to slot into the retainer. Oncefully engaged, the plank can be assumed to be aligned, as much aspractically possible, with the walling structure and with the previousplank.

In some embodiments, the facia comprises an outer flat that, when theplank is mounted to the walling structure, faces away from the wallingstructure, and the facia comprises on the outer flat one or more faciagrooves extending parallel to the joining lip.

The facia grooves provide one or more blind joints and, thereby, wheninstalled to a walling structure, a single plank may provide animpression of the presence of multiple planks spaced apart by eveninterstitial joint grooves, without requiring multiple planks. Thisallows larger planks to be used for larger areas in combination withsmaller planks where required. This facilitates the provision of auniform cladding while reducing the installation effort.

In accordance with a third aspect of the present invention, there isprovided a plank for an extruded plank façade system as defined in claim10. The façade system comprises a plurality of such planks as claddingsuitable for a vertical walling structure. The plank is of the typecomprising a facia, a joining lip, and an attachment hook structure.

The joining lip is recessed behind the facia and extends along a side ofthe facia to be at least partially overlapped by an adjacent facia ofanother plank to be provided and to define at least part of a jointgroove between the facia and the adjacent facia.

The attachment hook structure extends back behind the facia to allow theplank to engage, via the attachment hook structure, a retainer fixed tothe walling structure.

In the third aspect, the facia comprises an outer flat that, when theplank is mounted to a walling structure, faces away from the wallingstructure, and wherein the facia comprises on the outer flat one or morefacia grooves extending parallel to the joining lip.

Any embodiments of the third aspect may be combined with embodiments ofthe first aspect and/or the second aspect. The third aspect reduces theneed for additional alignment tools because a single plank provides theimpression of a two or more aligned planks.

When embodiments of the third aspect are combined with embodiments ofthe first aspect, this further facilitates the installation of alignedplanks, because a support-leg-providing rail improves the stability evenof a relatively larger plank during temporary positioning, and so largerplanks may be used instead of plurality of smaller planks that wouldotherwise be required to cover the same area.

When embodiments of the third aspect are combined with embodiments ofthe second aspect, this further facilitates the installation of alignedplanks, because alignment features on the joining lip help to ensurethat the interstitial groove space between plank facias (ie theinter-facia groove distance) corresponds to the one or more faciagrooves within a plank (ie to the intra-facia groove distance).

In some embodiments, the joining lip is recessed behind the flat of thefacia by a lip depth, and wherein the one or more facia grooves have afacia groove depth practically corresponding to the lip depth.

In some embodiments, the one or more facia grooves divide the facia intofacia strips of practically equal width.

In accordance with a fourth aspect of the present invention, there isprovided a plank arrangement for an extruded plank façade system asdefined in claim 13. The plank arrangement comprises a plank accordingto any embodiment of the first, second or third aspect, and saidretainer. The retainer comprises an attachment mechanism allowing theretainer to be fixed to a walling structure, a retaining lip forengagement with the attachment hook structure, and a spacing elementdefining a distance between the walling structure and the retaining lipwhen the plank is installed on the walling structure.

In some embodiments, the retainer comprises one or more retainerprotrusions and/or retainer recesses for alignment with correspondinglip recesses and/or lip protrusions on the joining lip of the plank.

In some embodiments, the attachment mechanism comprises a boltcomprising a bolt head arrangement providing the spacing element and theretaining lip.

The bolt and the bolt head arrangement may be unitary, made from thesame material. The bolt head arrangement may be made from a differentmaterial than the bolt. For instance, the bolt head arrangement may beovermoulded onto a bolt.

In some embodiments, the bolt head arrangement comprises a flangeextending around at least part of the circumference of the bolt head toprovide the retaining lip.

In some embodiments, the spacing element of the bolt head arrangement isprovided by a portion of a shaft of the bolt.

In some embodiments, the retainer is dimensioned to be smaller than thespace between the attachment hook structure and the rail, therebyavoiding interference of the retainer with the rail's abutment with anunderlying walling structure when the attachment hook structure is heldon the retaining lip.

In some embodiments, the retaining lip comprises an inclinedplank-engaging face to engage the attachment hook structure, such that,the deeper the attachment hook structure is set into the taperedplank-engaging face, the closer the plank is held on the wallingstructure.

Also disclosed herein is a retainer as described above, ie a retainer inisolation of a plank arrangement. Different variants of the retainer maycomprise any one of the features described above. For instance, in oneretainer variant, the retainer comprises a bolt comprising a bolt headarrangement providing the spacing element and the retaining lip. Thespacing element is provided by portion of the shaft of the bolt head.The retaining lip is provided by at least a portion of the flange of thebolt head arrangement. The retaining lip may comprise a taperedplank-engaging face. The plank-engaging face may be a frustoconicalportion of the bolt head arrangement facing in the direction of the tipof the bolt. Characteristically for a retainer used in the invention,the tapered plank-engaging face portion of the bolt head is on theunderside of the bolt head, the underside being the side from which thebolt shaft extends. The retainer variant comprising a bolt isdistinguished from a countersunk screw in that that the bolt headcomprises a spacing element on a portion of the shaft of the bolt, whichspacing element has a wider cross-section that the shaft. For instance,the spacing element may be a stepped portion of the shaft or of the bolthead that provides an annular seating surface to abut the wallingstructure. The retainer variant comprising a bolt is distinguished froma screw-in drawer handle in that the plank-engaging face portion of thebolt head has a straight, frusto-conical surface, so as to allow aretainer-engaging attachment hook structure to slide onto the retainer.Furthermore, the circumferential outer surface of the bolt head iscylindrical so as to provide a seating surface or contact lineperpendicular to the shaft.

The plank may be made from aluminium. The properties may be according toEN AW-6063T6 and BS EN 755-2:1997.

The plank may be provided with an anodised finish.

DESCRIPTION OF THE FIGURES

Exemplary embodiments of the invention will now be described withreference to the Figures, in which:

FIG. 1 shows a side section view of a part of a plank façade system inaccordance with embodiments of the invention;

FIG. 2 shows a side view of an embodiment;

FIGS. 3A to 3D show side views illustrating assembly steps of a plankfaçade system in accordance with the invention;

FIGS. 4A and 4B show a retainer arrangement for use with embodiments ofthe invention;

FIGS. 5A and 5B show another retainer arrangement for use withembodiments of the invention;

FIGS. 6A and 6B show another retainer arrangement for use withembodiments of the invention;

FIGS. 7A to 7C show different embodiments of the invention;

FIGS. 8A to 8D show side views illustrating further embodiments of theinvention; and

FIG. 9 shows a side view of another embodiment.

DESCRIPTION

FIG. 1 shows an overview of selected elements of a walling structure 1onto which a planks of the invention are installed as a façade system.The walling structure is part of, or attached to, a building. In thereading orientation of FIG. 1, the interior side of the building is onthe left side and the exterior side is right. The walling structurecomprises a building wall 2, such as cementitious board. Onto theoutside (ie, to the right in the reading orientation of FIG. 1) of thebuilding wall 2 is mounted via mullion brackets 4 a succession ofmullions 8 (only one mullion 8 is shown in FIG. 1). The mullion brackets4 hold the mullions 8 spaced from the building wall 2, set apart by aspace 6. Insulation material may be provided in the space 6. Theexternal side of the mullions 8 defines a plane 5 on which elements canbe mounted perpendicularly to the mullions. It is understood that theplane 5 is typically not a continuous surface area, but defined by asuccession of spaced-apart mullion surfaces. Across the spaced apartmullions 8 there are mounted a series of planks 10 to provide the outercladding for the building wall 2.

FIG. 2 shows a side view of a plank 10 of the invention. The plank 10 isextruded and has a uniform cross-section along its longitudinal extent,and so the features of the plank 10 can be described with reference tothe side view. To provide an illustration of the dimensions of theplank. the longitudinal extent of the plank may be in the region of oneor a few metres, as a trade-off between covering a large length whileremaining suitable for handling by a single person. The plank may bemanufactured to, or cut to, less than a metre as and when required. Theplank may have any height but will typically be in the region of 10 to40 cm high. The plank is in the region of about 2-3 cm deep fromwall-abutting surface to facia surface, and the sheet thickness may bein the region of 3 mm.

The external side is understood to be the side facing away from thebuilding to which the plank 10 is mounted. In the Figures, the plank 10is depicted with its external side on the right (right in the readingorientation of the Figures) and with the side to be mounted to abuilding on the left. The plank 10 comprises a generally flat mainsurface 12 constituting a facia, extending from a first facia edge 14 toa second facia edge 24. If installed as shown in FIGS. 1 and 2, thefirst facia edge 14 is the top edge of a facia and the second facia edge24 is the bottom edge of a facia.

At the first facia edge 14 the plank comprises a Z-bend backwards(backward with reference to the facia being the front side of theplank), the middle section of the Z-bend providing a first side wall 16and the end section of the Z-bend providing a shelf 20. The first sidewall 16 is angled at about a right angle (here, about 93 degreesincluded angle) relative to the main surface 12 and the shelf 20 isangled back by the same degree so as to extend parallel to the mainsurface 12, away from the main surface 12 and ending in a first plankedge 18. Due to the Z-bend, the shelf 20 is recessed behind the mainsurface 12 and extends along a side (here, the side constituted by thefirst facia edge 14) of the facia. The shelf 20 constitutes a joininglip to be overlapped by an adjacent plank. On the outer surface of theshelf 20 there are provided a plurality of ridges 22 (here: three ridges22A, 22B, 22C). The ridges 22 are spaced apart between the first sidewall 16 and the first plank edge 18. Each ridge 22 has a differentdistance relative to the first facia edge 14; a first ridge 22A isclosest to the first facia edge 14, a second ridge 22B is further awayand a third ridge 22C is furthest from the first facia edge 14. Thefirst distance between the first ridge 22A and the second ridge 22B isless than the second distance between the second ridge 22B and the thirdridge 22C. Eg, the first distance may be 7 mm and the second distancemay be 10 mm. The ridges 22 constitute alignment features of theinvention. Due to the different distances the ridges 22 are unequallyspaced apart with respect to the first facia edge 14.

Turning to the lower end, at the second facia edge 24 the plankcomprises a second side wall 26 that extends back behind the mainsurface 12 and ends in a second plank edge 28. The second side wall 26is angled at a practically right angle (here: about 93 degrees includedangle) and constitutes a rail of the invention. The second side wall 26provides a flashing function and could be referred as flashing rail. Thesecond plank edge 28 provides an abutment edge for abutting anunderlying surface, as will be described below.

Opposite the external side of the main surface 12, ie inside the plank10, between the first side wall 16 and the second side wall 26, spacedapart about 3 times further from the first side wall 16 than from thesecond side wall 26, there is provided a leg 32 extending back from theplank 10 and ending in a bend 30. The bend 30 constitutes an attachmenthook structure and comprises on the inside of the bend 30 aretainer-engaging surface 34, generally parallel to although somewhatinclined to the main surface 12, and a retainer-seating surface 35,generally perpendicular to the main surface 12. The retainer-engagingsurface 34 is inclined relative to the main surface, such that, thedeeper the attachment hook structure is set into the retainer (to beprovided), the closer the plank is held to a wall. The retainer-seatingsurface 35 is provided to rest on the retainer to be provided. The leg32 extends at an approximately right angle from the back of the mainsurface 12 (here: about 93 degrees included angle between the firstfacia edge 14 and the bend 30. The leg 32 is approximately parallel tothe second side wall 26.

On the rear side of the plank 10 between the first side wall 16 and themain surface 12 there is provided a first double-lip structure 17.Likewise, on the rear side of the plank between the second side wall 26and the main surface 12 there is provided a second double-lip structure27. The first double-lip structure 17 and the second double-lipstructure 27 each provide a cross-section providing a lateral screw-holebehind the facia, and are provided to allow structures such a lateralfinishing rail to be mounted to the lateral end of a plank.

In FIG. 2, a reference line 28A indicates the distance of the secondplank edge 28 from the main surface 12 and a reference line 34Aindicates the distance of the retainer-engaging surface 34 from the mainsurface 12. The second plank edge 28 is further away from the mainsurface 12 than the retainer-engaging surface 34 because the second sidewall 26 extends back from the main surface beyond the retainer-engagingsurface of the attachment hook structure.

Furthermore, a reference line 20A indicates the rear surface of theshelf 20 that is to come into abutment with a walling surface. Thereference line 28A is closer to the main surface 12 than the referenceline 20A by a distance corresponding to the sheet thickness of the shelf20. For instance, for planks with a sheet thickness of 3 mm, the secondplank edge 28 may be about 3 mm shorter than the wall-abutting rear sideof the shelf 20. This means that the second plank edge 28 extends backas far as the external surface of the shelf 20. As illustrated below,this arrangement achieves that second plank edge 28 of a subsequentplank sits flush on the shelf 20 of a preceding plank. For a firstplank, ie a plank that is installed without a preceding plank, it is anoption to use a starter bar of the same sheet thickness (eg, 3 mm), toensure a flush abutment.

It will be appreciated that the elements and components of the plank 10are of unitary character as the plank 10 is extruded. Elements of theplank 10, such as the ridges 22, or the leg 32 with the hookarrangement, can be manufactured in a single extrusion process, with auniform cross section along the longitudinal extent of the plank 10,without requiring subsequent pressing or stamping. This facilitates themanufacture of the plank 10.

Turning now to FIGS. 3A to 3D, there is illustrated a sequence ofinstallation steps for a succession of planks 10 (here: two planks 10Aand 10B) onto a plane 5. The plane 5 may be defined by a series ofspaced-apart mullions, as described in relation to FIG. 1. Attached tothe plane 5 is, by way of a bolt 38A, a retainer 38. The retainer 38 isa starter bar provided to support the first plank. Together with theelements defining the plane 5, the retainer 38 is considered a part of awalling structure. For the purposes of FIGS. 3A-3D, it suffices toappreciate that the retainer 38 comprises a lip suitable to receive insliding engagement a retainer-engaging surface of a plank 10.

Turning to FIG. 3B, a first plank 10A is hooked to the retainer 38 byway of the attachment hook structure, constituted by theretainer-engaging surface 34A, engaging the lip of the retainer 38. Theengaging surfaces of the attachment hook structure and of the retainerare each inclined relative to the plane 5, or, respectively, relative tothe main surface 12A of the first plank 10A, and so the first plank 10Ais drawn closer to the plane 5 the deeper the attachment hook structureis set in the retainer.

It is worth appreciating that the retainer-engaging surface 34A faces,although being tapered, generally in the direction of the facia, andthat the corresponding plank-engaging surface of the retainer faces,although being tapered, generally in the direction of the plane 5. Thisis due to the hooked engagement of the retainer-engaging surface withthe plank-engaging surface.

In FIG. 3B the plank 10A sits on the retainer 38 and the second plankedge 28A abuts the walling structure (i.e., it abuts a surface of thefixed retainer 38), whereby the plank 10A is propped up. The secondplank edge 28A inhibits a tilting forward of the plank 10A, andrestricts a tilting of the first (here: top) plank edge 18A away andforward from the plane 5. A tilting might otherwise occur because theattachment hook structure is positioned nearer the lower end than thetop end (here: about 3 times as far from the first facia edge than fromthe second facia edge), and so there is more mass above theretainer-engaging surface than below. Surprisingly, the plank 10A issecurely propped up by way of this configuration such that, in trials,it was not necessary for a co-worker to hold the plank 10A against theplane 5 before the plank 10A is secured by fixing means. It will beappreciated that without a retainer 38 forming part of the wallingstructure, a tilt of the plank 10A is still limited. With anappropriately designed retainer 38 in place, a tilt of the plank 10A canbe practically prevented.

Turning now to FIG. 3C, the plank 10A is fixed to the plane 5 by way ofa second bolt 38B engaging at the level of the shelf 20A. The secondbolt 38B is further used to secure another retainer 40 to the shelf 20A.In practice, this allows the other retainer 40 to be mounted to theplane 5 in the same action that is carried out to secure the first plank10A to the plane 5. The plank 10A is now considered to be part of thewalling structure. Furthermore, because the plank comprises an alignmentarrangement (see alignment features 22A-22C in FIG. 2), this facilitatesthat the retainer 40 is aligned at a pre-determined distance relative tothe first facia edge 14A. No additional temporary spacer is required toset the distance between the plank 10A and a succeeding plank. Thealignment will be described below.

In FIG. 3D, a second plank 10B is attached to the other retainer 40. Theplank 10B has the same configuration as the plank 10A and correspondingfeatures are designated by a suffix “-B” instead of a suffix “-A”.Similarly to the first plank 10A engaged in the first retainer 38, thesecond plank 10B is slotted into the other retainer 40 and propped up byway of the second plank edge 28B, such that the second plank 10B is heldin place without requiring the assistance of a co-worker. The secondplank edge 28B abuts the shelf 20A of the first plank 10A, now part ofthe walling structure. The second plank 10B can be bolted to the plane5, together with a third retainer (not shown) to continue the claddingprocess.

Furthermore, the second plank 10B is aligned (here: vertically aligned)with the first plank 10A. The interstitial space between the secondfacia edge 24B of the second plank 10B is at a pre-defined distance tothe first facia edge 14A of the first plank 10A. This facilitates theinstallation of a pre-defined joint groove distance between the twoplanks.

The advantage of the tilt-limiting, plank-propping rail, constituted bythe second plank edge 28 (in FIG. 3B: second plank edge 28A; in FIG. 3D:second plank edge 28B), is that taller planks may be used than wouldotherwise be possible safely. In particular, the retainers (in FIG. 3B:retainer 38; in FIG. 3D: retainer 40) can be dimensioned and positionedtowards the lower end of a plank without requiring a counterbalancingtemporary securing means (eg, a temporary retainer or assistance by aco-worker).

The retainers 38 and 40 have different designs. Retainer 38 is a starterbar and intended to support the first (here: lower) plank 10A, and isfixed directly to the plane 5, and not fixed onto a preceding plank. Assuch, the retainer 38 is wider, ie protrudes from the plane 5 further,than subsequent retainers, by an amount corresponding to the sheetthickness of the shelf 20. This is to ensure that the plank-engagingsurface of each retainer protrudes the same distance relative to theplane 5. The other retainer 40 is provided for a succession of planksand is intended to be fixed to a preceding plank. As such, the retainer40 comprises alignment features for alignment with a preceding plank.The starter bar does not require the same alignment features, althoughit may be provided with alignment features.

Turning now to FIGS. 4A to 6B, different clamping blocks 40A, 40B and40C are described. Each clamping block 40A, 40B, 40C constitutes aretainer for use with the invention.

FIG. 4A is an exploded view showing the shelf 20 of a first plank, andpart of a second plank 10B with a retainer-engaging surface 34 and aretainer-seating surface 35, and further a clamping block 40A and aseparate bolt 38. The clamping block 40A constitutes a retainer. Theclamping block 40A is a block of 11 mm depth and 24 mm height (from baseto lip). The clamping block has a length of about 25 mm (not visible inthe side view of FIG. 4A). On one side (the top side as illustrated inFIG. 4A), the clamping block 40A comprises, on the side to be facingaway from the plane 5 when mounted to a structure, a protrusion 44Aconstituting a retaining lip. On the rear (walling-structure-facing)side the protrusion 44A is tapered, or inclined relative to the plane 5,thereby to provide an inclined plank-facing edge. The protrusion 44A isspaced from the rear (walling-structure-facing) side of the clampingblock 40A by a spacer 46A. On its rear side, the clamping block 40Acomprises a plurality (here: three) grooves 42A each constituting aretainer recess providing an alignment feature for alignment with one ormore of the ridges 22A, 22B, 22C of the shelf 20. The ridges areunequally spaced apart from the first facia edge 14. The grooves 42A areunequally spaced apart and permit a tight seating of the clamping black40A on ridges 22 of the shelf 20 only in a few configurations (see FIGS.7A to 7C).

FIG. 4B shows the clamping block 40A fixed to the shelf 20 with the bolt38, using the ridge 22B as alignment feature, and with a second plank 10hooked onto the clamping block 40A. FIG. 4B shows that the interstitialgroove distance D between the planks is determined by the position ofthe clamping block 40A on the alignment feature of the preceding plank.Eg, if the clamping block 40A is mounted closer to the first facia edge(ie lower), because it is aligned with the ridge 22A instead of theridge 22B or 22C, the interstitial groove distance is shorter. If theclamping block 40A is mounted further away from the first facia edge (iehigher), the interstitial groove distance is longer. Furthermore, theretainer-seating surface 35 sits on the protrusion 44A (see FIG. 4A) ofthe clamping block 40A and this achieves a good alignment of theretainer-seating surface 35 relative to the first plank 10.

FIGS. 5A and 5B show an arrangement corresponding, except fordifferences set out below, to the arrangement of FIGS. 4A and 4B. Thesame numerals are used for corresponding elements. Instead of ridges22A, 22B, 22C, the shelf 20 in FIG. 5A comprises a plurality (here:three) of grooves 23A, 23B, 23C. The grooves are unequally spaced apartfrom the first facia edge 14. The clamping block 40B is a block of 11 mmdepth and 24 mm height (from base to lip) and has a length of about 25mm (not visible in the side view of FIG. 5A). On one side (the top sideas illustrated in FIG. 5A), the clamping block 40B comprises aprotrusion 44B constituting a retaining lip. On the rear(walling-structure-facing) side the protrusion 44B is tapered, therebyto provide an inclined plank-facing edge. The protrusion 44B is spacedfrom the rear (walling-structure-facing) side of the clamping block 40Bby a spacer 46B. On its rear side the clamping block 40B comprises aridge 42B constituting a retainer protrusion providing an alignmentfeature for alignment with one of the grooves 23A, 23B, 23C of the shelf20. It can be appreciated that the distance of the clamping block 40Brelative the first facia edge 14 depends on which one of the grooves23A, 23B, 23C is engaged by the ridge 42B.

FIG. 5B shows the clamping block 40B fixed to the shelf 20 with a bolt38, using the groove 23B as alignment feature, and with a second plank10 hooked onto the clamping block 40B. The interstitial groove distanceD between the planks is determined by the position of the clamping block40B on the alignment feature of the preceding plank.

FIGS. 6A and 6B show another arrangement alternative to the arrangementshown in FIGS. 5A and 5B. The same numerals are used for correspondingelements. Instead of a clamping block 40B, the FIG. 6A arrangement showsa fixing screw 40C that is configured to provide the function of aclamping block. The fixing screw 40C constitutes an attachment mechanismwith a bolt head comprising a circumferential flange 44C. Thecircumferential flange 44C constitutes a retaining lip. The bolt head isstepped relative to the thread portion to provide a seating face 46Cthat constitutes a spacing element defining a distance between thewalling structure (ie the external surface of the shelf 20) and theretaining lip. The fixing screw 40C comprises a tip 42C that provides analignment feature with one of the grooves 23A, 23B or 23C of the shelf20.

FIG. 6B shows the fixing screw 40C fixed to the shelf 20, using thegroove 23B as alignment feature, and with a second plank 10 hooked ontothe fixing screw 40C. The interstitial groove distance D between theplanks is determined by the position of the fixing screw 40C on thealignment feature of the preceding plank. The advantage of thecircumferential flange 44C, or a flange that extends over at least aportion of the circumference of the bolt head, is that it provides anupward-facing lip feature regardless of the angular orientation of theretainer relative to the bolt axis. Furthermore, instead of a contactline, the circular flange provides a contact point for an attachmenthook structure, which further reduces potential misalignment.

Furthermore, the provision of a fixing screw reduces the number ofcomponents a worker has to handle. Ie, instead of bolts and clampingblocks, a worker requires only bolts comprising a bolt head arrangementthat provides the retainer functionality.

FIGS. 7A, 7B and 7C show three configurations derived from the alignmentfeatures. Continuing from the example shown in FIGS. 4A and 4B, FIGS. 7Ato 7C show three different groove distances D1, D2 and D3, respectively,that can be set by positioning a clamping block (or fixing screw)relative to the ridges 22A, 22B, or 22C of the joining lip.

In a first configuration, shown in FIG. 7A with reference to FIG. 4A,the first and third grooves 42A (see also FIG. 4A) engage with thesecond and third ridges 22B and 22C. In the first configuration, thesecond groove and the first ridge 22A do not engage and are alsopositioned to avoid interfering with the coupling of the engaging ridgesand grooves. The first configuration sets a groove distance D1.

In a second configuration, shown in FIG. 7B with reference to FIG. 4A,the first and second grooves 42A (see also FIG. 4A) engage with thefirst and second ridges 22A and 22B. In the second configuration, thethird groove and the third ridge do not engage and are also positionedto avoid interfering with the coupling of the engaging ridges andgrooves. The second configuration sets a groove distance D2 that is lessthat the groove distance D1.

In a third configuration, shown in FIG. 7C with reference to FIG. 4A,the first groove 42A (see also FIG. 4A) engages with the first ridge22A. In the third configuration, the second and third grooves and thesecond and third ridge do not engage and are also positioned to avoidinterfering with the coupling of the engaging ridge and groove. Thethird configuration sets a groove distance D3 that is less that thegroove distances D1 or D2.

It will be understood that the configurations of FIG. 7A, 7B and 7Ccould be achieved with the clamping block 40B shown in FIGS. 5A and 5B,or with the fixing screw 40C shown in FIGS. 6A and 6B.

To better appreciate the benefit if the alignment features 22, 23, and42, it is worth bearing in mind that a plank may be several metres longbut may be positioned with the help of a few retainers, each only a fewcentimetres wide, spaced apart along the length of the plank. As such,one retainer may be in the region of one or more metres spaced from thenext retainer for the same plank. It would in the absence of alignmentfeatures be difficult for a worker not to accidentally position tworetainers at different height levels, eg, one retainer at a correct(intended) height, eg height level A, and to position another retainerat a wrong height, eg height level B. Due to the tolerances, a slightoffset may not be discovered at the time of installation. A provisionallowing a worker to rely on the correct positioning of a few,pre-defined alignment features helps to avoid misalignment problems. Inthe particular example, there are only 3 different levels (here: top,middle, base) at which a clamping block can be mounted, which reduces,and practically eliminates, the risk of an alignment error. There may bea small number, such as 2, 3, 4 or 5 alignment positions, to assist withthe positioning of the retainer. Furthermore, the unequal spacingfurther assists the eye in identifying the correct alignment position,as can be imagined. For instance, for a group of six alignment features(ridges or grooves) each vertically equally spaced apart, it may bepossible to accidentally confuse the third and fourth feature. If atleast a few of the features are unequally spaced apart, eg in threegroups of two features, the eye can identify the third and fourth lineas the upper line of the middle group or the lower line of the middlegroup, and in practice the unequal spacing therefore reduces the risk ofmisalignment.

The sequence of FIGS. 8A to 8D is provided to illustrate embodimentscomprising one or more facia grooves to provide the impression of aplurality of aligned planks. To provide a context for the embodiments,FIG. 8A is provided as a copy of the arrangement shown in FIG. 3D,showing however only reference numerals 10A and 10B of a first andsecond plank, respectively. As such, FIG. 8A shows a plurality (here:two) planks to cover a given surface area.

FIG. 8B shows a single plank 50 that corresponds in principle to theplank 10 illustrated in FIG. 2. The plank 50 comprises between the firstfacia edge and the second facia edge a facia groove 52 that divides thefacia into a first facia strip 51A and a second facia strip 51B. Thefacia groove 52 extends parallel to the facia edges and is positionedhalf-way between the first facia edge and the second facia edge, and sothe first and second facia strips 51A, 51B have about equal height.

FIG. 8C shows the plank 50 installed on a plane 5. Comparing FIGS. 8Aand 8C, the outward-facing contour of the plank 50 corresponds closelyto the outward-facing contour that would be provided by two alignedplanks 10A and 10B. Viewed from an external side (in the readingorientation of FIG. 8C, from the right), the plank 50 provides a similarvisual appearance to the arrangement of FIG. 8A, while requiring only asingle plank 50 to be installed to cover the given surface area coveredin FIG. 8A. Note that plank 50 comprises a single attachment hookstructure near the lower (lower in the reading orientation of FIG. 8C)end of the plank 50. Due to the support leg function of the rail at thelower end, the plank 50 is stably supported on the correspondingretainer until it is fixed at the shelf level by bolts.

FIG. 8D shows, to provide a further example, a plank 60 comprising aplurality (here: two) facia grooves 62A and 62B that are equally spacedapart between the first facia edge and the second facia edge, to dividethe facia of plank 60 into three equal facia strips 61A, 61B and 61C.The height of each facia strip 61 may correspond to the height of afacia of a single plank 10.

It can be appreciated that large planks with multiple facia strips arecombinable with single-facia planks such as plank 10 shown in FIG. 2 tofacilitate the cladding process by reducing the number of planks to bemounted to a walling structure.

The provision of a plank-supporting rail assists with the temporarysupport of larger planks, corresponding to the area covered by multiple(eg three) single planks, even if these larger planks are only supportedby a single attachment hook structure at the lower end of the plank.

FIG. 9 shows another embodiment of a plank 70. The plank corresponds tothe plank 10 described in FIG. 2 and so the same reference numerals areused for corresponding features. The description for correspondingfeatures is not repeated for brevity. Instead of a plurality of ridges(see ridges 22 in FIG. 2), the plank 70 comprises on the shelf 20 aplurality of grooves 23A, 23B, 23C. The groove arrangement correspondsto the arrangement shown in FIGS. 5A to 6B, and lends itself, forinstance, for use with a screw-type retainer.

In contrast to the FIG. 2 embodiment, the plank 70 does not comprisedouble-lip structures (see double-lip structures 17 and 27 in FIG. 2) inthe edges between the first side wall 16 and the main surface 12, andbetween the second side wall 26 and the main surface 12. The plank 70comprises a side double-lip structure 19 provided on an inside of thefirst side wall 16. The side double-lip structure is clear of the mainsurface 12 and so avoids contact with the main surface 12. The spacingfrom the main surface 12 is sufficient to allow a small amount ofdeformation of the double-lip structure 19 without it coming intocontact with the main surface 12. This reduces the risk of a deformationon the main surface that may otherwise potentially occur on the facia ifa fixing means is attached just behind it. The plank comprises ahook-located lip structure 31 on the leg 32. The hook-located double-lipstructure 31 is clear of the main surface 12 and so avoids contact withthe main surface 12. Furthermore, the hook-located double-lip structure31 is located between the leg 32 and the first side wall 16. As and whena minor deformation occurs upon fixing a screw into the screw holeprovided by the double-lip structure 31, such a deformation (if at alloccurring) urges the plank toward the retainer. This prevents apotential up-lifting, or tension urging the plank 70 out of a retainer,when a screw is fixed to mount an end cover laterally onto the plank byway of the hook-located double-lip structure 31.

In embodiments with facia grooves, such as the plank 50 or 70, adouble-lip structure providing a lateral screw hole may be positioned ona side wall of the facia groove. This allows a lateral screw hole to beprovided without the lateral screw hole contacting the main surface, orwithout the structure forming the screw hole contacting the main surfaceupon expansion when a screw is fixed into it.

1-20. canceled
 21. A plank for an extruded plank façade systemcomprising a plurality of such planks as cladding suitable for avertical walling structure, the plank being of the type comprising afacia, a joining lip, and an attachment hook structure, wherein thejoining lip is recessed behind the facia and extends along a side of thefacia to be at least partially overlapped by an adjacent facia ofanother plank to be provided and to define at least part of a jointgroove between the facia and the adjacent facia, wherein the attachmenthook structure extends back behind the facia to allow the plank toengage, via the attachment hook structure, a retainer fixed to thewalling structure, wherein the plank further comprises a rail to atleast partially conceal the attachment hook structure, and wherein therail extends back from the facia beyond the attachment hook structure,whereby, when the plank is attached to the walling structure by way ofthe attachment hook structure on the retainer, the rail abuts thewalling structure, thereby limiting a tilt of the plank about theattachment hook structure.
 22. The plank according to claim 21, whereinthe attachment hook structure has a contact level with the wallingstructure where it attaches to the retainer, wherein the rail has acontact level with the walling structure where it contacts the wallingstructure, and wherein the contact levels of the attachment hookstructure and of the rail are spaced apart less than the width of thejoining lip.
 23. The plank according to claim 21, comprising a lateralscrew hole structure behind the facia, the allow another structure to bemounted to the lateral end of the plank, wherein the lateral screw holestructure is spaced from the facia.
 24. The plank according to claim 23,wherein the lateral screw hole structure is provided by a double-lipstructure.
 25. The plank according to claim 23, wherein a lateral screwhole structure is located on the hook structure.
 26. The plank accordingto claim 21, wherein the joining lip comprises a plurality of one of lipprotrusions and lip recesses, the lip protrusions and lip recesses,respectively, constituting alignment features for said retainer.
 27. Theplank according to claim 26, wherein the lip protrusions are provided byridges, and/or wherein, respectively, the lip recesses are provided bygrooves.
 28. The plank according to claim 26, wherein the alignmentfeatures constituted by said plurality of lip protrusions and liprecesses, respectively, are unequally spaced apart with respect to thedistance from the facia.
 29. The plank according to claim 21, whereinthe attachment hook structure comprises a retainer-engaging face that isinclined relative to the plank plane, such that, the deeper theattachment hook structure is set into the retainer, the closer the plankis held on the walling structure.
 30. The plank according to claim 21,wherein the facia comprises an outer flat that, when the plank ismounted to the walling structure, faces away from the walling structure,and wherein the facia comprises on the outer flat one or more faciagrooves extending parallel to the joining lip.
 31. The plank accordingto claim 30, wherein the joining lip is recessed behind the flat of thefacia by a lip depth, and wherein the at least one facia groove has afacia groove depth practically corresponding to the lip depth.
 32. Theplank according to claim 30, wherein the at least one facia groovedivides the facia into facia strips of practically equal width.
 33. Theplank according to claim 21, comprised in a plank arrangement for anextruded plank façade system further comprising said retainer, whereinthe retainer comprises an attachment mechanism allowing the retainer tobe fixed to a walling structure, a retaining lip for engagement with theattachment hook structure, and a spacing element defining a distancebetween the walling structure and the retaining lip when the plank isinstalled on the walling structure.
 34. The plank according to claim 33,wherein the retainer comprises at least one of a retainer protrusion anda retainer recess for alignment with one of a corresponding lip recessand lip protrusion, respectively, on the joining lip of the plank. 35.The plank according to claim 33, wherein the attachment mechanismcomprises a bolt comprising a bolt head arrangement providing thespacing element and the retaining lip.
 36. The plank according to claim35, wherein the bolt head arrangement comprises a flange extendingaround at least part of the circumference of the bolt head to providethe retaining lip.
 37. The plank according to claim 35, wherein thespacing element of the bolt head arrangement is provided by a portion ofa shaft of the bolt.
 38. The plank according to claim 33, wherein theretainer is dimensioned to be smaller than the space between theattachment hook structure and the rail, thereby avoiding interference ofthe retainer with the rail's abutment with an underlying wallingstructure when the attachment hook structure is held on the retaininglip.
 39. The plank according to claim 33, wherein the retaining lipcomprises an inclined plank-engaging face to engage the attachment hookstructure, such that, the deeper the attachment hook structure is setinto the tapered plank-engaging face, the closer the plank is held onthe walling structure.
 40. A walling structure comprising one or moreplanks according to claim 21.